CSharpGL.ZeroIndexPointInTriangleSearcher.Search C# (CSharp) Method

        internal override uint Search(RenderEventArgs arg,
            int x, int y,
            uint lastVertexId, ZeroIndexRenderer modernRenderer)
        {
            // 创建临时索引
            OneIndexBuffer buffer = Buffer.Create(IndexBufferElementType.UInt, 3, DrawMode.Points, BufferUsage.StaticDraw);
            unsafe
            {
                var array = (uint*)buffer.MapBuffer(MapBufferAccess.WriteOnly);
                array[0] = lastVertexId - 0;
                array[1] = lastVertexId - 1;
                array[2] = lastVertexId - 2;
                buffer.UnmapBuffer();
            }
            // 用临时索引渲染此三角形图元（仅渲染此三角形图元）
            modernRenderer.Render4InnerPicking(arg, buffer);
            // id是拾取到的Line的Last Vertex Id
            uint id = ColorCodedPicking.ReadStageVertexId(x, y);

            buffer.Dispose();

            // 对比临时索引，找到那个Line
            if (lastVertexId - 2 <= id && id <= lastVertexId - 0)
            { return id; }
            else
            { throw new Exception("This should not happen!"); }
        }